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Spiders are one of the most numerous groups of terrestrial predators and these are found in diverse environments such as agroecosystems and nearby areas. Research on spider diversity in agroecosystems is important for following changes in fauna brought about by management. This work evaluated spider richness, abundance, and species composition similarity between a rice agroecosystem and adjacent environments at different development stages of the crop. The study area was Estação Experimental do Arroz, in Cachoeirinha, Rio Grande do Sul state, south Brazil. A sweep net was used with 50 passes per transect as a sample; transects were set in a rice field, in a grassland (a former rice field), and in a nearby forest edge. We sampled 2,717 spiders; 78.7% were young and most adults were females (1.22:1). Representatives of 15 families were collected, the most dominant being Oxyopidae (n = 753) and Araneidae (n = 371). Representatives of 85 morphospecies (adults) were sampled, with the most abundant being Oxyopes salticus (n = 120) and Alpaida veniliae (n=62). Most species were found on the forest edge (62), followed by rice crop (38) and grassland (26). There were significant differences in spider species composition among environments and rice culture periods. Only eight morphospecies were common to all areas; forest edge had the higher number of exclusive species (42). Rice had a typical composition of species, probably due to the ecological selectivity of the spiders. Diversity was higher in the forest edge, suggesting this environment as an important refuge for the fauna living in areas with high anthropogenic disturbance as agroecosystems.

The male of Dubiaranea difficilis is described and illustrated for the first time. New geographic records of this species are provided, and its potential distribution is modeled using MAXENT. The actual and potential distribution of Dubiaranea difficilis proved to be much larger than the hitherto known records. This species inhabits at least in three ecoregional sectors in Argentina (northwestern area, central Sierras, and the Pampas), and is also likely that inhabits in Brazil and Bolivia. Possible causes of its wide and environmentally heterogeneous distribution are discussed.

Neopisinus gen. nov. é proposto com designação da espécie-tipo Neopisisnus fiapo sp. nov., com base em ambos os sexos, do Rio Grande do Sul, Brasil. Neopisinus distingue-se de todos os gêneros de Spintharinae pelo palpo do macho com enorme condutor trífido, com duas projeções afiladas e uma com ápice bifurcado; pela forma característica da apófise tegular de theridioideos com um lobo terminal e outro dorsal. Nas fêmeas, epígino com aberturas inconspícuas junto à fenda transversal no terço anterior e, internamente, por um espessamento mediano-longitudinal tubular, por onde correm os ductos de copulação em seu percurso inicial. Neopisinus urucu sp. nov. é descrita do norte do Brasil, com base em ambos os sexos. Sete espécies são transferidas de Episinus para Neopisinus: N. bigibbosus (O. P.-Cambridge, 1896), N. bruneoviridis (Mello-Leitão, 1948), N. cognatus (O. P.-Cambridge, 1893), N. gratiosus (Bryant, 1940), N. longipes (Keyserling, 1884), N. putus (O. P.-Cambridge, 1894) e N. reci...

Com a intenção de conhecer a diversidade da araneofauna relacionada à cultura do arroz, foi realizado um inventário deste agroecossistema ainda pouco estudado em sua biodiversidade. Foram realizadas 17 amostragens na Estação Experimental do Arroz (EEA), do Instituto Rio Grandense do Arroz (IRGA), Cachoeirinha, RS (50º58'21"W; 29º55'30"S) entre outubro de 2004 e junho de 2005, em três períodos: antes do arroz ser semeado, durante o desenvolvimento do arroz e após a colheita. As coletas foram efetuadas no período matinal utilizando rede-de-varredura (35 cm de diâmetro), 50 golpes em cada um dos quatro transectos por amostragem. Coletou-se um total de 918 aranhas distribuídas em 14 famílias, com predomínio de Araneidae, Anyphaenidae, Oxyopidae e Tetragnathidae. Entre os indivíduos adultos, foram determinadas 38 morfoespécies, as mais abundantes Alpaida veniliae (Keyserling, 1865), Tetragnatha nitens (Audouin, 1826), Ashtabula sp.1 e Tetragnatha aff. jaculator, as quat...

New species of Alpaida (Araneae, Araneidae), complementary descriptions and taxonomic note. Alpaida arvoredo sp. nov. is described based on males and females from Arvoredo Island, Santa Catarina coast, Brazil. The male was described associated to A. hoffmanni . The correct male of A. hoffmanni is described for the first time. Alpaida caramba sp. nov., based on both sexes, is described from Rio Grande do Sul, Brazil. The males of Alpaida kochalkai A. lomba Levi, 1988, are described for the first time.

Três espécies de Cryptachaea Archer, 1946 são descritas, duas delas para o Brasil: C. amazonas sp. nov. da Reserva Florestal Adolpho Ducke, Manaus, Amazonas e Cryptachaea maldonado sp. nov. da Base de Operações Geólogo Pedro de Moura, Porto Urucu, rio Urucu, Coari, Amazonas, com base em machos. Uma nova associação de macho e fêmea é proposta para Achaearanea hieroglyphica (Mello-Leitão, 1940). O macho da Guiana Francesa, atribuído à última espécie, é considerado uma espécie nova de Cryptachaea, C. ingijonathorum. O macho de Achaearanea tingo Levi, 1963 é descrito pela primeira vez. Novas ocorrências são listadas para A. trapezoidalis (Taczanowski, 1873).

In this paper seven new species of Latonigena Simon, 1893 are described, including the first descriptions of males of this genus. Latonigena beni sp. nov. is described from Bolivia and Brazil and six species are described exclusively from Brazil: L. colombo sp. nov. from Paraná; L. lami sp. nov. from Paraná and Rio Grande do Sul; L. santana sp. nov., L. sapiranga sp. nov. and L. taim sp. nov. from Rio Grande do Sul; L. turvo sp. nov. from Tocantins, Santa Catarina and Rio Grande do Sul. Latonigena africana Tucker, 1923 is transferred to Trichothyse Tucker, 1923 with basis on the morphological characters.

Vesicapalpus serranus sp. nov., do Estado do Rio Grande do Sul, é descrita, ilustrada e são apresentados dados ecológicos desta espécie. A fêmea de Vesicapalpus simplex Millidge, 1991 é descrita, ilustrada e novos dados de distribuição geográfica são fornecidos.

Theridiosoma caaguara sp. nov. do Estado do Rio Grande do Sul, Brasil, é descrita e ilustrada. Baalzebub baubo Coddington, 1986 é registrada pela primeira vez para o Brasil, ampliando-se a distribuição conhecida de Epilineutes globosus (O. P.-Cambridge, 1896), Naatlo splendida (Taczanowski, 1873) e Ogulnius obtectus O. P.-Cambridge, 1882.

We evaluated spider guild abundance and vegetation complexity in riparian forests in southern Brazil in four distinct river basins over 2 yr. We compared spider guild abundance among rivers, habitats (edges vs. forest interior), and against vegetation complexity. We also compared spider assemblages between juvenile and adults in terms of guilds. Of 42,057 spiders sampled, 79% were juveniles and 21% were adults. Space-web weaving was the most abundant guild whereas cursorial hunters was the least abundant one. Weaving spiders dominated over hunters (59% vs 40.58%, respectively). Thirty-four families were recorded; ambush hunters totaled 11 families; space web sheet builders and hunting runners had eight families each and there were seven families for orbicular web builders. Space web sheet builders dominated on all levels: among rivers and habitats (edges and forest interior). Unexpectedly, spider guilds did not seem to be influenced by environmental complexity, given the variables measured, under a Canonical Correspondence Analysis. There was an interaction between guild relative abundance and ontogeny, since the proportion of the space web sheet builders guild among adult spiders was larger than the proportion among juveniles, with a decrease in proportion of adults especially for hunting runners.